1. Field of the Invention
The present invention relates to an image display method and an apparatus therefor, and more particularly an image display method for interpreting geometrical pattern data such as font, planar pattern or stereo pattern defined in the three-dimensional (3D) space, attribute data such as color or pattern thereof, and description data such as data relating to illumination or projection by means of a computer and calculating, generating and displaying an image, and an apparatus therefor.
2. Related Background Art
In the image display method and apparatus for visually displaying the geometrical data defined in the three-dimensional space, it is generally necessary to define the direction of the view field for the visual display and the position of the original point for projection. Such direction of the view field and position of the original point for projection have been designated have been manually controlled for example by a mouse, a joy stick, a keyboard, a track ball or a controller composed of plural switches.
In such conventional system, in case of moving the direction of the view field and the original point for projection at the same time, it has been necessary to manipulate two input devices with two hands at the same time. Therefore, if another operation is also required, the operator has to extend the hand to another input device. Such operation tends to cause confusion in the operator and errors in the applications requiring rapid operations. On the other hand, in order to achieve the movement of the direction of the view field and that of the original point for projection with a single input device, it has been necessary to sacrifice some of the six freedoms in total for the direction of the view field and the position of the original point for projection, or to select the movement of the direction of the view field or that of the original point for projection, by means of a switch.